JPH1190943A - Production of cellulose triacetate film and clip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent troubles which lower productivity even when the width of a web is increased by specifying the ratio of an optional transportation length of a tenter to the total length in the transportation direction of parts in which a web is held by clips in a tenter of the same length. SOLUTION: A T-shaped flip 12 with a large area and a T-shaped flip 13 are combined alternately and arranged on the web side and and the out side respectively so that a web holding area and a holding length in the transportation direction are made almost continuous. The clips are connected by a chain to travel along a rail 11. The ratio Lr=Ltt/Lt of an optional transportation length Lt (m) to the total length Ltt (m) in the transportation direction of parts in which the web is held by clips in a tenter of the same length Lt is made to be 1.0<=Lr<=1.99. Since the clips are in the form of the combination of reciprocal T-shaped types, a continuous state without gaps in the transportation direction is made, a tension distribution to the web is made uniform, and productivity can be improved to the widening of the web.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellulose triacetate for high productivity while maintaining good flatness of a cellulose triacetate film used for a silver halide photographic material or a support of a liquid crystal image display device. The present invention relates to a method for producing a film. In particular, the present invention relates to a method for producing a cellulose triacetate film having excellent flatness and stable productivity by improving a tenter clip, and a clip suitable for the production.

[0002]

2. Description of the Related Art As shown in FIG. 1, a method for producing a cellulose triacetate film by a solution casting method is an endless support having a mirror-finished surface of a cellulose triacetate solution (hereinafter also referred to as "dope"). (For example, a belt or a drum), which is cast from a die 2 on a die 3, the dope film is peeled off at a peeling point 4 (also referred to as a web), and drying is completed through a drying device having a group of rolls 6 to obtain a cellulose triacetate film. It is.

The slow rate of film formation by the solution casting method is a major problem. In recent years, the film is conveyed by a tenter 8 instead of a group of rolls as shown in FIG. (For example, JP-A-62-115035 or 62-4662).
No. 6). However, when the tenter 8 is used, there is a gap between the divided clips due to the structure of the apparatus, and as a result, the tension distribution to the clip holding portion and the web around those gaps becomes uneven, and the wrinkles of the web become uneven. However, partial deformation occurred, or streaks such as blown unevenness appeared, and it was difficult to obtain a satisfactory product in terms of quality.

[0004]

There has been a need to improve the above problems, but there is a concern that the problems may be increased by widening the web in order to further improve the productivity. I was

An object of the present invention is to solve the above-mentioned problems caused by the use of a tenter, and to provide a method for producing a cellulose triacetate film which does not cause the above-mentioned troubles which impair productivity even when the width of the web is increased. To provide.

A second object of the present invention is to provide a clip used to achieve the above object.

[0007]

The above object is achieved by the following (1) to (4).
The problem was solved by the configuration (7).

(1) In producing a cellulose triacetate film by a solution casting method using a tenter, an arbitrary transport length Lt (m) of the tenter and a clip in the tenter having the same length as Lt are used. Lr with respect to the sum Ltt (m) of the lengths in the transport direction of the part holding
= Clip wherein Ltt / Lt is 1.0 ≦ Lr ≦ 1.99.

(2) A clip characterized in that, in producing the cellulose triacetate film, a portion for holding a web is arranged without a gap when viewed in a web width direction.

(3) In producing the cellulose triacetate film, a portion for holding the web has a T-shape, and the T-shape is alternately arranged in the opposite direction. The clip according to (2).

(4) In preparing the cellulose triacetate film, an arbitrary transport length L of the tenter is used.
t (m) and the total length Lt of the length in the transport direction of the portion where the clip in the tenter having the same length as Lt holds the web
Lr = Ltt / Lt with respect to t (m) is 1.0 ≦ Lr ≦
1. A method for producing a cellulose triacetate film, characterized by using a 1.99 clip.

(5) A method for producing a cellulose triacetate film, characterized in that, in producing the cellulose triacetate film, a clip in which a portion for holding a web is arranged without a gap when viewed from the web width direction is used.

(6) In producing the cellulose triacetate film, it is preferable that a portion for holding the web has a T-shape, and a clip in which the T-shape is alternately arranged in an opposite direction. The method for producing a cellulose triacetate film according to (5), which is characterized in that:

(7) In producing the cellulose triacetate film, the ratio Wr = Wt of the width Wt of the portion where the tenter holds the web to the width Wf (m) of the web is used.
/ Wf is in the range of 0.004 ≦ Wr ≦ 0.05, and the web holding area St (m ² ) and the web area Sf
A method for producing a cellulose triacetate film, wherein the ratio of (m ² ) Sr = St / Sf is Sr ≧ 0.003.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail.

The clips used in the present invention are so-called ordinary polyester-type clips, modified clips described later, and pin-type clips. When a clip is simply referred to, it is referred to unless a polyester stretch mold is refused. In the case of a pin-type clip, the term pin-type clip is used. The I-shaped or T-shaped clips of the present invention have such words prepended to the clips, but may be simply abbreviated as clips.

In the present invention, the width of the dope film (a film formed by evaporating the solvent to form a soft but somewhat firm film by evaporation from a die) on a support is called "web" if it is wide to increase productivity. Although it is better, it cannot be made too wide due to various restrictions, so it is from about 1 m to about 6 m.

FIG. 3 is a sectional view of a solution casting film forming apparatus in which the tenter 8 is installed after the drying apparatus 5, and is used together with FIG. 2 as the solution casting film forming apparatus of the present invention.

FIG. 4 is a plan view of a part of an I-shaped clip row of the present invention in which a portion for holding a web is disposed without a gap when viewed from the web width direction, and 9 is disposed on the near side. When viewed from the web side with an I-shaped clip (foreground), it is on the near side. Reference numeral 10 denotes an I-shaped clip (back) on the back side. These I-shaped clips cover the gap between the clips in the front row of clips with the I-shaped clip at the back, so that there is no clipping on the web, thus improving the quality and widening the web. The response to is fully performed. Further, the I-shaped clip row is provided in the first aspect of the present invention.
It is a clip that satisfies.

FIG. 5 is a plan view of a portion of a T-shaped clip array of the present invention in which clipping is further enhanced. Particularly, clips having a shape similar to a T in a Roman alphabet as shown in FIG. 5 are arranged alternately in the opposite direction, and a T-shaped clip 12 having a large area on the web side is a T-shaped clip (normal).
And Reference numeral 13 denotes a T-shaped clip having a large area on the outside, which is referred to as a T-shaped clip (reverse). The webs are arranged so as to be intertwined with each other so that the area where the web is held (clipping) and the length that is held in the transport length direction are almost constant. Reference numeral 11 denotes a rail along which clips are connected by a chain (not shown). 6 and 7 are perspective views of one embodiment of a (normal) (reverse) T-shaped clip.

FIG. 8 is a schematic plan view in which a T-shaped clip row is incorporated in a tenter. A sprocket 15 allows the clips 12 and 13 to rotate endlessly. Even if the interval between the clips 12 and 13 and the next clip is the interval between the normal clips, the interval between the clips is substantially the same as the interval between the clips, since the T-shape is alternately arranged.

FIGS. 9 and 10 show another example of the T-shaped clip.
It is a side view of an example. 17 'is a shoe having a large area and 17 is a shoe having a small area. Reference numerals 16 and 16 'denote fixing stands corresponding to this.

FIG. 11 is a schematic perspective view showing three-dimensionally adjacent clips by actually combining forward and reverse T-shaped clips.

The conditions satisfying the present invention will be described.

Lt (m): Arbitrary transport length with a tenter Ltt (m): Total length in the transport direction of a portion in the tenter of the same length as Lt that holds a web in the transport direction Lr = Ltt / Lt: arbitrary transport length L with tenter
This is the ratio of t (m) to the sum of the lengths in the transport direction of the portion where the clip in the tenter having the same length as Lt holds the web.

1.0 ≦ Lr ≦ 1.99: In the clip array used in the conventional tenter, Lr is 0.8 to 0.9.
It seems to be around 95. In the present invention, since the gap is covered by another clip, Lr is 1.0 or more, and the flatness of the edge of the web can be improved. In particular, the T-shaped clip indicates that the closer the value of Lr is to 1.99, the better the gap is covered.

Other conditions of the present invention will be described.

Wt (m): The width of the portion where the tenter holds the web (that is, the width of the two opposite T-shaped widths in FIG. 3 and is doubled because it is on both sides of the web) Wf (m) ): Width of the web (this is the width of the web, but strictly speaking, it is the width when the web is flattened at the tenter entrance because there is slack in the web). Wr = Wt / Wf: The clip for the entire width of the web is held. Length ratio St (m ² ): Within an arbitrary transport length of the tenter,
In the case of a clip (hereinafter, simply referred to as a clip refers to a polyester stretch type clip), it is the total area (area on both sides) of a portion that comes into contact with the web and applies pressure to hold the web. In the case of a pin-type clip, the area surrounded by pins outside the aggregate of the plurality of pins attached to the fixing base of the pin-type clip is denoted by St.

Sf (m ² ): Web area (area of both sides of the web) Sr = St / Sf: Ratio of area of clip holding portion to web area 0.004 ≦ Wr ≦ 0.05: tenter If the holding width is too narrow (Wr <0.004), the web is liable to tear due to its own weight, and more than the holding strength can be secured (Wr <0.004).
> 0.05) Even if the clip is held, the yield of the film is reduced.

Sr ≧ 0.003: Web tear at the tenter holding portion caused by the weight of the web is Sr <0.00.
Therefore, it is desirable to implement within the scope of the present invention.

By satisfying such conditions, the present invention is achieved, and a wide range of cellulose triacetate films of high quality and excellent productivity can be obtained. In other words, the clip of the present invention has a clip area and length that is nearly twice as long as the total length of the conventional clip because the clip has a T-shaped combination that is the reverse of the conventional clip. By providing another clip outside the gap between the clips as described above, it is apparently close to a continuous state without a gap in the transport direction, and the tension distribution on the web is made uniform, and the holding area is increased, so that the plane is flat. It is possible to stably produce a cellulose triacetate film having extremely excellent properties. In addition, even with a wider web, it can be produced with almost the same quality as a normal width web,
Productivity can be improved.

[0032]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto.

(Basic conditions) The conditions for preparing the cellulose triacetate film described here are basic and are the basis of the conditions in the following examples. Using a dope consisting of 100 parts by weight of cellulose triacetate, 400 parts by weight of methylene chloride, ethanol and 12 parts by weight of TPP, a web was cast from a die onto a stainless belt running endlessly having a mirror surface so that a web width became 2 m, and a belt was formed. Is peeled at about one rotation, the residual solvent amount of the web immediately after the peeling is set to 130%, and after the peeling, the web is drawn around by the roll group 6 and dried, and when the residual solvent amount of the web becomes about 45% by weight, The film was introduced into a tenter and dried while maintaining the width. The drying was completed by a drying device, and both ends of the film were cut off to obtain a cellulose triacetate film having a thickness of 125 μm.

For the residual solvent used in the present invention, the web sampled at the measurement point was placed in a weighing bottle, the web weight A (g) was weighed, and the web sample was later heated to 115 ° C.
After heating for 1 hour at room temperature, the mixture is cooled to room temperature so as not to adsorb moisture, the weighing bottle is weighed, and the weight of the dry web B (g)
Is calculated according to the following equation.

Residual solvent amount (% by weight) = {(AB) / B} × 100 (Measurement of flatness) A cellulose triacetate film sample was cut out from the wound film roll, and cut from the center side edge of the film of the tenter holding portion. A total of 2 lines up to 40 mm at intervals of 20 mm toward the center of the film were selected at 5 points at intervals of 50 mm in the transport direction, and each point was scanned 10 mm using a surf coder with a stylus type 3D surface roughness meter manufactured by Kosaka Laboratories. The flatness was evaluated by the average value of the obtained center line average roughness: Ra (μm) at 10 points.

Example 1 A cellulose triacetate film was prepared by changing Wr, Sr and Lr as shown in Table 1, and the flatness was measured. The results are shown in Table 1.

[0037]

[Table 1]

(Results) The Lr in the present invention was adjusted to 1.02 to 1.0.
As a result of changing to 80, excellent flatness could be obtained in each case. Further, as a result of performing Wr and Sr in the present invention with Lr set to 0.9, good flatness results were obtained. Also L
Even when r was set to 1.80 and Wr and Sr were excluded from the present invention, excellent flatness could be obtained. Lr, Wr for comparison
When both Sr and Sr were excluded from the present invention, the web was torn and no film was obtained.

[0039]

As described above, by using a clip in which the gap between the clips is not overlapped by another clip, the quality can be stably produced even with a wide web, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a solution casting film forming apparatus.

FIG. 2 is a sectional view of a solution casting film forming apparatus using a tenter.

FIG. 3 is a sectional view of a solution casting film forming apparatus using a tenter after a drying apparatus.

FIG. 4 is a plan view of a part of an I-shaped clip row.

FIG. 5 is a plan view of a part of a T-shaped clip row.

FIG. 6 is a perspective view of one embodiment of a T-shaped clip (positive).

FIG. 7 is a perspective view of one embodiment of a T-shaped clip (reverse).

FIG. 8 is a schematic plan view in which a T-shaped clip row is incorporated in a tenter.

FIG. 9 is a side view of one embodiment of a T-shaped clip (reverse).

FIG. 10 is a side view of one embodiment of a T-shaped clip (positive).

FIG. 11 is a schematic perspective view showing a three-dimensional combination of T-shaped clips.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Web 2 Die 3 Support 4 Peeling point 5 Drying device 6 Roll (group) 7 Drying vent 8 Tenter 9 I-shaped clip (front) 10 I-shaped clip (back) 11 Rail 12 T-shaped clip (positive) 13 T-shaped clip (reverse) 14 Lever 15 sprocket 16 Fixed base (reverse) 16 'Fixed base (correct) 17 Shoe (reverse) 17' shoe (correct) 18 T-shaped clip (correct) 19 T-shaped clip (reverse) )

Claims (7)

[Claims] In producing a cellulose triacetate film by a solution casting method using a tenter, an arbitrary transport length Lt (m) of the tenter and a clip in the tenter having the same length as Lt are used to form the web. Ratio Lr = total length Ltt (m) of length of holding portion in conveyance direction
A clip, wherein Ltt / Lt satisfies 1.0 ≦ Lr ≦ 1.99. 2. A clip, wherein a portion for holding a web is arranged without a gap when viewed from a web width direction in producing the cellulose triacetate film. 3. The method for producing the cellulose triacetate film, wherein a portion for holding the web has a T-shape, and the T-shapes are alternately arranged in opposite directions. Item 3. The clip according to Item 2. 4. An arbitrary transport length Lt of a tenter for producing the cellulose triacetate film.
(M) and the total length Ltt of the length in the transport direction of the portion where the clip in the tenter having the same length as Lt holds the web
(M) and the ratio Lr = Ltt / Lt is 1.0 ≦ Lr ≦
1. A method for producing a cellulose triacetate film, characterized by using a 1.99 clip. 5. A method for producing a cellulose triacetate film, characterized in that, in producing the cellulose triacetate film, a clip in which a portion for holding a web is arranged without a gap when viewed from a web width direction is used. 6. The method for producing the cellulose triacetate film, wherein a portion holding the web has a T-shape, and a clip in which the T-shape is alternately arranged in an opposite direction is used. The method for producing a cellulose triacetate film according to claim 5, wherein 7. In producing the cellulose triacetate film, the ratio Wr = Wt / W of the width Wt of the portion where the tenter holds the web to the width Wf (m) of the web is used.
f is in the range of 0.004 ≦ Wr ≦ 0.05, and the web holding area St (m ² ) and the web area Sf
A method for producing a cellulose triacetate film, wherein the ratio of (m ² ) Sr = St / Sf is Sr ≧ 0.003.